High-speed commutator



Nov. 3, 1953 D. E. sT. JOHN HIGHSPEED COMMUTATOR Filed July 9, 1951 Patented Nov. 3, 1953 HIGH- SPEED COMMUTATOR Dale E. St. John,

Northrop Aircraft, Inc.

corporation of Californi Application July 9, 1951, Serial No. 235,768

13 Claims.

This invention relates to a means and method of commutating a large number of information channels into one common lead for the purpose of transmitting information out of these information channels on a single carrier.

Among the objects of the invention are:

To provide commutation at a high rate;

To provide a commutator without brushes or commutator segments;

To provide commutation without physical contact of circuit controlling elements;

To provide commutation by ionic control of gaseous discharge tubes;

And to provide a relatively simple high speed commutation device.

The above objects vare accomplished in the present invention by the utilization of a radio frequency eld to excite a plurality of gaseous discharge lamps arranged so that a high speed rotor distributing this field excites or ionizes each lamp consecutively until the commutation cycle is completed. When each lamp is ionized by the R. F. field, the lamp passes a direct current, developing a voltage that is used to operate a gating circuit.

Referring to the single ligure which shows diagrammatically the present invention as applied to a telemetering circuit, a motor I is connected to rotate an excitation rotor 2 having an arm 3. Arm 3 comprises a shield 4 carrying an arm electrode 5 ending in an excitation tip S tangent to the circle of rotation of the arm 3.

Arm electrode 5 is connected through a suitable brush 'i and stationary ring 8 to a radio frequency oscillator i0, this oscillator being adapted for continuous excitation of tip B.

Positioned concentrically in a circle around arm 3 and just outside the circle of rotation of tip 5 are a plurality of two electrode cathode glow tubes NE1, NE2, etc. Up to 40 of such tubes, well known in the art and usually filled with neon, can readily be utilized for example.

Several of these neon tubes, for example three adjacent tubes NE1, NEz and NEa, have one electrode thereof (cathode) connected in parallel to a gate diode V1, the anode 20 of which is energized through resistance R1 and positive potential line 2 l The anode 20 oi' tube V1 is valso connected to ground through a germanium diode GD1 and a diode V5, this latter diode having its anode 22 connected to ground, with its cathode 23 connected to the negative side of germanium diode GDL A bias line 25 is provided, energized by a bias Long Beach, Calif., assignor to Hawthorne, Calif., a a

source 2S providing a bias to the cathode 21 of gate V1 through cathode resistance R9.

As will be Seen later, the three glow tubes NE1, NEz and NES combine to produce a synchronizing pulse once per revolution of arm 3.

The other glow tubes NE4 to NE1L are respectively connected to information channels INFO1 to INFO-n, respectively, through respective gate diodes V2 Vn, and also respectively through germanium diodes GDz to GD to a main channel line 30. Each of the gate diodes V2, V3 Vn is biased from bias 26 through bias line 25 and through respective bias resistors R10 Rn in the same manner as described `for gate diode V1.

Main channel line 30 is led through an input resistor R5 to the grid 38 of a triode amplifier tube V7, and the combined channel output is taken from the anode 36 of this triode V7 by an output line 31.

Grid 33 of triode V7 is also fed by an anode 39 of a bias diode Ve through bias resistor Re, this latter diode being shunted by a bias cell 40 in series with a resistance Rv on one side and resistance Ra on the other. The junction between R7 and cell 40 is grounded. The cathode 4| of bias diode V6 is connected to the output of an amplifier, inverter, and D. C. restorer 42, the input of which is connected to al1 of the other electrodes (-anodes) of the glow tubes NE1 to NE. through an isolating capacity 45. These latte:- anodes are also energized from a positive potential source Sa through limiting resistor 46. (Motor I is energized from source Sb.)

The operation of the above described commutator is as follows:

Diode tubes V1, V2, Vs, V4, etc. are connected to information channels INFO1, INFOz INFO and master pulse channel 30. When these diodes conduct, they effectively short out the information voltage through series resistors R1, R2, R3, R4, etc., one in each channel. The bias 26 voltage is connected to the cathode 2'? of the gating diodes V1 V11 to bring all of these cathodes lbelow ground potential insuring that the points A, B, C, D, etc. will be at ground potential or lower, with maximum information voltage.

Each neon NE1, NEz, etc. is connected to the positive D. C. potential source Sa, which has a potential lower than the extinguishing voltage of the lamps. When any neon lamp NE1 NE1L is ionized by the R. F. field upon close approach thereto of the energized tip 6, this lamp `conducts current, thereby developing a voltage mitting the voltage at point E to develop avoltage on the grid 38 of the amplifier tube V1 through the germanium diode GD1 and resistor Rs. Lamps NE1, NEz and NEa are mountedphysically so close together so that the field on tip 6 ionizes lamp NEz before lamp NEi extinguishes, lamp NEs is ionized before lamp NEz extinguishes.

With this arrangement an output pulse threel times the Width of an information pulse .isgenerated and creates a master synchronization and 1 pulse once per revolution of the excitation rotor.

Lamps NEi, NES, NEG and the rest of the neon lamps `in the commutation-.cycle arephysically spaced so that each lamp extinguishes before the next lamp ionized thereby providing -a .time separation between the gating of each information channel.

When the excitationtip 6- ionizes lamp NEA., a voltage is developed across cathode resistance R10 which causesgatediode Vzto out on, there.- by allowing the information voltage at informa.- tion channel INFO1 to developl a voltage at the grid of amplifier tube V7.

age on the associated INFO channel is .gated and fedto the amplier tube V7. This process continues untilall the INFC). channelsvr have been gated, at which' time the excitation tipis again in apositionto cause the master synchronization pulse to -be generated.

The germanium diodes GD1, GDz, GDS, GD4, etc. are connected so that'a. positive information voltage at points A, B, C and D willhave a low impedance path to the grid 3.8 of amplifier tube V7, but will see a high impedance back into any other information channel. Diode V5 is connected to conduct when a negative voltage appears at point. F. A negative voltage at point F would. be. present when, poi-nts A, Br C, D,. etc.. are negative during the time the gating diodes V1, V2, etc.. are. conducting.. This is caused by the fact that germanium diodes d'o not have an infinite back impedance. Since the anode 22 of diode Vv is connected to ground,l any negative. voltage that would be present at point F is reduced to an insignificant value.

Bias diode Vs and bias cell' 4t are connected so that normally bias diode Ve provides a. current path through resistors R7 and Rs, thereby developing a negative voltage on the end of' re.- sistance R1 presented to grid 33 of amplifier tube Vv. This negative voltage across' resistance Rv puts a negative voltage on the grid 38` of amplier tube Vv through a voltage divider consisting of resistances R16, R5 and the diode V to ground. Since resistance @f5 is connected in series with the voltage supplied to the neon lamps NEi NEn,eaehtin1e-alamp conducts,anegative voltage is developed across resistance 46. This voltage is fed to the input of the amplifier, inverter and' D. C. restorer 42 whichA causes a positive voltage to be developed across resistance Ra each time a neon lamp NE fires to gate a channel., This positive voltage across resistance Rc raises the cathode 4l of bias diode Vs above groundhigh enough so that it stops conducting, thereby removing the negative voltage across re- As-each neon lamp is ionized infturn,vthe information in terms of voltsistance Rv. This action allows the grid 38 of tube V1 to go to a positive potential proportional to the information voltage being gated. By adjusting the resistance of resistance R7, the amplitude of the channel synchronizing pulse can be set to any desired percentage of the maximum information voltage.

lSumming up vthe operation of the synchronizingpulsecircuits, just above described, it can be said that each time an information channel is gated, the grid of amplifier tube V1 rises from a presetnegative value to ground when a channel with zero information is gated or to a positive value proportionali to the information voltage Whennaichannelwith information voltage present is gated.

Y TheR. oscillator HJ used to ionize the neon lamps NE1 NE is conventional and need only supply enough R. F. eld at tip 6 for proper ionization and excitation of the neon lamps.

Motor fl; which turns the `'excitation rotonis preferably a constant-.speed --motor turningatfapproximately 15,006 R1 P. M. for example, dependeingA on` .the desired*y commutation frequency;

When 40 information channels are used, forexample, these channelsA can all be sampled 250 times per second, .asampling speed not ati present knownv to be practicatvvith any mechanical commutator.

While in order -to comply with the statute, the

invention has been described in` language more;

or less specinc as to structural features, it is -to be understood that the invention is not limitedto the specific'featuresshovvn, but-that themeans and construction herein disclosedfcompri-seapreferred form of putting the invention into eect, and they invention is.. therefore, claimed in. any; of its forms or modifications within the legitimate and valid sco-pe of the appended claims.

What isclaimed is:v

1. A commutating device comprising a .rotor having a conducting area thereon adapted to. be energized toV produce a eldextending beyond said rotor,l and ay plurality of gaseous discharge tubes positoned in an area adjacent the arc of said area whereby as said area is rotated said tubes will beserially .exposed to the eld, extend-I ing from said area without contacttherewith.v

2. A commutating device comprising a rotor having a conducting area, means for rotating saidA rotor tocause said area to describe an. arc, means. for energizing said area while rotating with high frequency energy to provide a field around said area extending beyond said area, a plurality ofA gaseous discharge tubes positioned 1n an arc adjacent.A the arc described by said area with each of said tubes positioned to be influenced by the field on said area as said area is rotated, and means for energizingv said tubes at a potential' below the burning potential thereof', whereby as said area is rotated. said. tubes Will ignite to pass current only When in the iield of said area.

3. Apparatus in accordance with claim 2 wherein at least a portion of said tubes are spaced with relation to the extent ofv said eld so that an ignited tube Will extinguish before the next tube is ignited.

4. Apparatus in accordance with claim 2` wherein at least a portion of said tubes are spaced with.

relation to the extent of said eld so that an ignited tube will remain ignited until the next tube is ignited.

5. Apparatus in accordance with claim 2 wherein a plurality of' information channels are provided each with a gate, each of said gates being connected to be opened or closed in accordance with the ignition and extinction of one of said tubes, and a common output line connected to said gates.

6. Apparatus in accordance with claim 2 wherein a portion of said tubes are spaced with relation to the extent of said eld so that an ignited tube will remain ignited until the next tube is ignited, the remainder of said tubes being more widely spaced so that an ignited tube will extinguish before the next tube is ignited.

7. Apparatus in accordance with claim 6 wherein a single gate is connected to be controlled by the condition of said closely spaced tubes, a plurality of energized information channels each provided with a gate, said latter gates being connected to be respectively controlled by said wider spaced tubes, and a common output line connected to said gates whereby a relatively long energy pulse followed by a succession of shorter energy pulses will be present in said common output line as said area is rotated.

8. The method of commutation which comprises energizing a plurality of cold cathode gaseous glow discharge tubes at a potential just below the burning voltage thereof, and serially exposing said tubes to a high frequency electrical field suiiicient to ionize each tube, when exposed, to the extent that the exposed tube will pass current.

9. The method of commutation which comprises continuously energizing a plurality of cold cathode gaseous glow discharge tubes at a potential just below the burning voltage thereof, and serially exposing said tubes in a predetermined repeating order to a high frequency electrical eld sufdcient to ionize the exposed tube, only, to the extent that it passes current to develop a voltage for electronic gating purposes.

l0. A commutating device comprising a plurality of cold cathode gaseous glow discharge tubes positioned in adjacent locations, an electrical radiator member, means for energizing said radiator member with radio frequency oscillations to produce an electrical eld extending beyond said radiator member, and means for moving said radiator member past said tubes in a predetermined cycle whereby said tubes are serially exposed to said extending field to cause said tubes to conduct only when exposed to said field.

11. A commutating device comprising a plu rality of gaseous discharge tubes positioned in predetermined relation, an electrical radiator member adapted to be energized to produce a radio frequency field extending beyond said radiator member, and means for continuously mov- 6 ing said radiator member in a path adjacent said tubes to serially expose said tubes to said radio frequency eld in a predetermined cycle, whereby as said field is moved said tubes may be ignited to pass current only when exposed to said field.

12. A commutating device comprising a plurality of gaseous discharge tubes positioned in a predetermined relation, an electrical radiator member adapted to be energized to produce a radio frequency eld extending beyond said radiator member, means for energizing said tubes at a potential lower than the burning potential thereof, and automatic mechanical means connected to said radiator member to move said member in cyclic manner past said tubes to expose each of said tubes to said radio frequency field, whereby said tubes will ignite to pass current only while exposed to said radio frequency eld.

13. A commutating device for cyclicly applying electrical information in a plurality of information inputs to a single output line, which comprises a plurality of gaseous discharge tubes positioned in predetermined relation, an electrical radiator member adapted to be energized to produce an oscillating field extending beyond said radiator member, circuit means for constantly energizing said tubes at a potential just below the burning potential thereof, a plurality of normally conducting gate means respectively connected at one side thereof to a control point in each conducting circuit of said tubes where a potential change occurs during conduction of its respective tube, the other side of each gate means connected respectively to said information inputs, each said gate means being open to short out its respective input when its respective discharge tube is non-conducting, a rectifying diode connected to the junction of each of said information inputs and its respective gate means. the other sides of said rectifying diodes connected directly to said output line, and means for moving said radiator member in a continuous cyclic manner past said tubes to serially expose said tubes to said field, whereby each time a tube is so exposed it is caused to conduct current and produce a voltage closing its respective gate, thereby allowing the potential of its respective information input to pass through its respective rectifying diode and appear on said output line.

DALE E. ST. JOHN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,169,409 Dey Aug. 15. 1939 2,287,881 Holden June 30, 1942 

